Azalea plant named ‘Roblen’

ABSTRACT

A new and distinct variety of  Azalea  plant named ‘Roblen’, characterized by its unique blooming time, upright, dense and globose growth habit, and attractive single to semi-double red flowers.

Genus species: Rhodendron hybrid.

Varietal denomination: ‘Roblen’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct variety of evergreenAzalea of the genus Rhododendron and a member of the Ericaceae family.This new Azalea variety, hereinafter referred to as ‘Roblen’, wasdiscovered by Robert Edward Lee in August, 1998 in Independence, La.‘Roblen’ originated from a controlled breeding program in Independence,La. The objective of the breeding program was to create new Azaleavarieties which have unique blooming periods, bloom colors, bloom forms,bloom sizes, and growth habits. ‘Roblen’ originated from a cross made byMr. Lee in April, 1996 of the cultivar ‘Watchet’ (unpatented) as thefemale, or seed, parent with the proprietary hybrid seedling number 2-32(unpatented) as the male, or pollen, parent.

Asexual propagation of the new plant cuttings has been under Mr. Lee'sdirection at the same location. The new plant retains its distinctivecharacteristics and reproduces true to type in successive generations.The plant cannot be reproduced true from seed.

SUMMARY OF THE INVENTION

The following are the most outstanding and distinguishingcharacteristics of this new cultivar when grown under normalhorticultural practices in Independence, La.

-   -   1. The unique spring, summer, and fall blooming.    -   2. A red flower color Red Group 44C with dotting color Red Group        53C.    -   3. Single to semi-double flowers ranging in size from 1¾″ to 2¼″        in diameter.    -   4. Easily propagated with semi-hardwood cuttings in late spring        through the summer.    -   5. Fast growth rate under normal fertilization and moisture        conditions.    -   6. Upright, dense and globose in nature.    -   7. Good specimen plant.    -   8. Desirable in planters.    -   9. Makes a very good hedge or screen.    -   10. Very good foundation plant.    -   11. Does well as an understory plant in a woodland garden.    -   12. Hardy to Zone 7.    -   13. Attracts butterflies.

DESCRIPTION OF THE DRAWINGS

This new Azalea hybrid variety is illustrated by the accompanyingphotographic prints in which:

1. The photograph at the top of the sheet is a close-up showing flower,foliage, and stem color as well as flower size and form.

2. The photograph at the bottom of the sheet shows the upright, denseand globose growth habit of a young three gallon plant.

The colors shown are as true as is reasonably possible to obtain byconventional photographic procedures. Colors in the photographs mayappear different than actual colors due to light reflectance. The colorsof the various plant parts are defined with reference to The RoyalHorticultural Society Colour Chart. Description of colors in ordinaryterms are presented where appropriate for clarity in meaning.

BOTANICAL DESCRIPTION OF THE PLANT

The following is a detailed description of the new variety of Azaleabased on my observations made of 2 year old plants grown in 3 galloncontainers in wholesale commercial production practices, in greenhouses,and in established landscape plantings in Independence, La.

Distinctive Characteristics

TABLE 1 R. oldhamii ‘Fourth of Characteristic ‘Roblen’ ‘Watchet’ ‘Carla’July’ Height (Mature) 4-5′ 2-3′ 2-3′ 8-10′ Width (Mature) 3-4′ 3-4′ 3-4′6-7′ Flower Diameter 1¾-2¼″ 3½-3¾″ 2½-4″ 1¾-2¼″ Flower Form Single/semi-Single Semi- Single double double Flower Color Red G. 44C Red G. Red G.Red G. 39A 49B 40C Flowers per 2-3 1-2 2-3 2-4 Terminal Bloom PeriodApril May April Late June > ″ Late July > Frost Frost Petal/Petaloid5-10   5 5-10 5 Number Hardy Zone 7   6 7 7 Stamen Number 5 10 0 7-10Stamen Type Some Petaloid Non- Petaloid Non-Petaloid Petaloid

The female, or seed parent, of ‘Roblen’ is the Azalea ‘Watchet’; amoderate pink, single, late blooming, low compact grower. ‘Watchet’ isan unpatented Robin Hill hybrid developed by Robert Gartrell in Wycoff,N.J. Mr. Gartrell started his hybridization in 1937 to produce hardy,late blooming Azaleas. ‘Watchet’ is the result of a cross between theSatsuki Hybrid ‘Amagasa’ (unpatented) and the Robin Hill Hybrid ‘LadyLouise’ (unpatented).

The male, or pollen, parent of ‘Roblen’ is the product of thepollination of the cultivar ‘Carla’ (unpatented) by the cultivar ‘Fourthof July’ (unpatented). This proprietary hybrid seedling, number 2-32 wascrossed with ‘Watchet’ to produce the new cultivar ‘Rublen’. ‘Roblen’differs from number 2-32 primarily in flower color. The parentage of thenew variety can be summarized as follows:‘Watchet’×#2-32 (‘Carla’×‘Fourth of July’)

‘Carla’ is a strong reddish orange, semi-double, mid-season blooming,low compact grower developed by North Carolina State University andLouisiana State University.

Robert Edward Lee's hybridization program was conducted with emphasis Onspecies that are not commonly found in the genetic make-up of thepresent day hybrids. The ‘Fourth of July’ cultivar which Mr. Leeobtained from Dr. Thornton in 1981 is a heavy summer and fall bloomingplant, not like the Rhododendron Species Foundation form. The flowerbuds form on new growth and start blooming about July 1. Mr. Lee usedthis cultivar to cross with existing hybrids which have a tendency tobloom in the fall and which are also fairly hardy. As expected theresulting seedlings are heavy summer and fall bloomers with veryimpressive spring blooms also.

-   Classification:-   Botanic: Rhododendron hybrid ‘Roblen’.-   Form: Upright, dense, and rounded.-   Height: 4-5′.-   Width: 3-4′.-   Growth habit: Upright, dense and globose. Fast growth rate under    normal fertilization and moisture conditions.-   Growth rate: In a period of six years from a rooted cutting the    plant reaches a height of 3 feet and a spread of 2 feet. The growth    rate is normally about 6 to 8″ per year; the plant reaches a height    of 4 to 5′ at maturity while maintaining a dense habit due to the    abundant branch development.-   Foliage: Alternate, simple, evergreen, pubescent, elliptic, and    varying in size from 1¾″ to 2¼″ long and ¾″ to 1⅛″ wide. The margins    are entire, with a petiole 3/16″ to ¼″ long. Midveins and laterals    are impressed on the upper leaf surface and prominent on the    underside. The base of the leaf is cuneate to attenuate and the apex    is acute to mucronate. The upper surface of the immature leaves is    dull, pubescent, and is Yellow-Green Group 144A and the underside is    Yellow-Green Group 146D, pubescent, and matte. The upper surface of    the mature leaves is Yellow-Green Group 147A, glossy and slightly    pubescent and the underside is Yellow-Green Group 146B, matte, and    pubescent. The immature petioles, midribs, and veins are    Yellow-Green Group 146C. New growth is pubescent. These hairs are    initially soft and white and cover both sides of the leaf with a    higher concentration on the petioles and veins. They are slightly    curled, flat, and range in length from 1/64″ to 1/32″. As the growth    matures much of the leaf pubescence is lost; however, the stems,    petioles, and leaf veins retain this pubescence which becomes more    setaceous and darker in color (Brown Group 200B) through the growing    season. The reduction of pubescence makes the leaf appear darker    than Yellow-Green Group 147A.

In 2001, the date of initial spring growth was March 8, in Independence,La. After the initial spring flush there was almost continuous growthuntil that fall ending November 5, also in Independence, La. When grownin full sun, the internode length of this plant is ¼″ to ⅝″; when grownin light shade the internode length is ⅜″ to ¾″. As would be expected aplant grown in shade results in a taller, less dense plant with largerleaves.

The average length of terminal growth of the initial spring flush isabout 5″ for a plant in full sun and about 7″ when grown in shade. Thisgrowth should not be trimmed since it will produce flowers starting inlate July. As the plant continues to grow through the summer and fallmore flower buds are produced, which mature and bloom until frost. Thisremaining growth produces about 4″ to 5″ of height. As cool weatherapproaches, some of the flower buds become dormant. These buds bloom inApril of the next year.

-   Stems: The young stems are Yellow-Green Group 146C and densely    clothed with spreading white glandular hairs. During the second    growing season they become Greyed-Green Group 197B, glabrous and    rugose. The pith is solid and uniform. Young and older stems are    densely branched.-   Buds: Tight buds at ½″ are ovate and acuminate Yellow-Green Group    146D with a hairy pubescence Brown Group 200B. The buds are borne in    clusters of 2 to 3, and are sheathed by a pair of modified leaf    bracts which are from ¼″ to ½″ long, persistent, and Yellow-Green    Group 147A. The pedicel is ⅜″ to ⅝″ long, pubescent, and Yellow    Green Group 145C. The calyx is ⅛″ to 3/16″ long, Yellow-Green Group    144B, funnel shaped, persistent, and pubescent. The five imbricated    sepals are lanceolate and joined at the base to form a cup. As the    buds swell the bud sheath matures to a Greyed-Orange Group 165A,    falls off, and reveals the flower color Red Group 44C.-   Flowers: Perfect, single to semi-double, Red Group 44C (upper    surface and under surface), glabrous, open funnel shaped, 1¾″ to 2¼″    in diameter by 2″ to 2¼″ in depth, borne on current season's growth,    non-fragrant; they last on the plant in the garden 5 to 6 days.    These are five true petals which are fused at the base, elliptic,    and have wavy margins. These petals are 1½″ to 2″ long, ¾″ to 1¼″    wide, and have rounded apexes and entire margins. Three out of five    petals are dotted with Red Group 53C. There are 5 non-petaloid    stamens which are 1″ to 1¼″ long. The filaments are Red Group 39B,    the anthers are Greyed-Orange Group 167B, and the pollen matures to    Yellow Group 11B. The 0-5 petaloid stamens are from ¼″ to ¾″ long,    ⅛″ to ⅜″ wide, and odd shaped. The margins are entire and the apexes    rounded. The pistil is single, non-petaloid, 1½″ to 2″ long and Red    Group 46A. The ovary is densely glandular-setose and has five    locules. The capsule matures in about 5 months, in Independence,    La., to about ¼″ to ½″ long; it has a persistent style, is    Yellow-Green Group 146B, and contains from 100 to 400 nonwinged    seeds. Normally fruit set is not heavy. There is a 2 to 3 week    flowering period in April in Independence, La. Flowering resumes in    July as the new buds mature and continues until frost which can be    as late as November or December in Independence, La. Azaleas    blooming at this time of year attract butterflies in profusion.-   Culture: Grows well in a wide range of conditions, tolerates sun to    shade. Prefers a moist, well-drained soil that is rich in organic    matter. Responds well to mulching and medium applications of    fertilizer; prefers ph 5.0 to 5.5. Very little pruning is needed;    adaptable to container and above ground planters; makes a good    foundation plant or informal hedge with excellent foliage and flower    contrast. Ideal for coastal regions and warmer parts of Piedmont.    Propagated with semi-hardwood cuttings in late spring through the    summer.-   Pests: Lace wing and spider mites can be a problem.

1. A new and distinct variety of Azalea plant named ‘Roblen’ asillustrated and described.